Cellular telephones are becoming more commonplace, more inexpensive, and more standardized with each passing day. The system with which cellular phones operate must accommodate both the forward calling from the cellular telephone to another phone of any type, and the reverse calling of the cellular telephone from another phone of any type.
The origins of modern cellular communication dates back to the 1920's with experimental equipment being first installed in police vehicles in some large cities. Commercial applications of mobile radio were not significant until after World War II. The needs of the military greatly accelerated development of radio technology, and these early advances appeared in commercial products available in the early 1950's.
The early systems began with simplex operation, and progressed to duplex mobile telephone frequency pairs in the 150 MHz and 450 MHz bands. In the mid 1960's, Bell Laboratories began working on the details of a system which evolved into the cellular system of today. Today's cellular system can accommodate some variance with respect to the equipment and manner of accessing the system. For Example, U.S. Pat. No. 4,658,096 to West, Jr. et al, and entitled "System for Interfacing a Standard Telephone Set with a Radio Transceiver" illustrates one such method for interfacing. U.S. Pat. No. 4,788,711 to Michael Nasco, Jr. et al, and entitled "Apparatus and Method for a Cellular Freeway emergency Telephone Service" illustrates a method of using roadside cellular phones which is currently in use on the nation's highways. Both of these patent applications are incorporated by reference herein.
Parameters which had to be settled on included spectrum allocation, digital signalling and control, the geographical subdivisions from which radio control is accomplished, commonly known as cell sites, and the allocation and use of frequency control channels for message carrying capability. The original cellular spectrum allocation was for a total of 40 MHz, with 20 MHz providing service in each direction between the base station and the mobile station. A total of 666 channels, each 30 KHz wide, were designated for each direction. The channels were divided equally into two competing bands. These bands were the A band, also known as the "non-wireline" band, and the B band, also known as the "wireline" band. The original intent was that in each market, the local exchange carrier (which was publicly regulated) would be granted a license for the B band, while the A band would be granted to a private business on the basis of competitive application.
As time progressed, and with the break-up of the smaller telephone carriers, the A band and the B band have developed into competing systems. Each may have its own commercial carrier associated with a city served by a cellular system. Further, the service level and rate structure offered by the A band and B band carriers will typically be quite different. Current cellular phone systems do not allow for the automatic selection of, or change in the selection of a particular carrier band.
If such a selective change were possible, flexibility of operation would occur. Whole groups of users of a certain type could switch between the two types of cellular carriers, and thus the carriers would begin to behave more competitively. Unfortunately, the lack of the ability to easily switch back and forth is a major shortcoming of conventional cellular technology.
As will be shown, conventional cellular use involves not only a complex and secure communications scheme, but also a scheme of similar complexity to identify users of the system and apply charges for use of the system properly. When a user makes a call through the cellular system, the user's equipment identifies them by a mobile identification number, MIN. Although this number is not required to be a standard telephone number as defined by the North American Dialing Plan, it usually is such a standard number.
The North American Dialing Plan, also known as the North American Numbering Plan is a method of identifying telephone trunks in the public network of North America, called World Numbering Zone 1 by the CCITT. The plan has three ways of identifying phone numbers in North America, a three digit area code, a three digit exchange or central office code and a four digit subscriber code. Other countries have more complex numbering schemes.
One designation for area code is the designation NPA, while a corresponding designation for the seven digit local phone number is NXX. The combination is sometimes known as NPP/NXX. The number of NPA codes is nearing depletion. Bellcore, the Bell Communications Research group, was formed at divestitute to provide certain centralized se4rvices to the seven regional Bell Holding companies. It serves as a focal point for telephone communications matters of the federal government. This group was instrumental in the formation of the NPP/NXX plan. Thus the typical mobile identification number is typically complete with area code and accompanying seven digits, similar to a dedicated wired telephone number.
The number alone is not much use without some reference to compare it to. A subscriber data base, either local or long distance, must be addressed to verify the legitimacy of the user. In this manner, lost or stolen mobile or portable phones can be rendered unusable by removing the user's identification number or access go-ahead from the home service cellular switch data base. By home service, is meant the area in which the cellular phone was based, usually related to an address where the bills are paid and especially related to the area code and trunk, NPP/NXX assigned to the conventional cellular phone.
Where the user of the portable or mobile phone is "roaming," or out of his usual home geographic area, there are what will be referred to as service cellular system cell sites and switch matrix where the user is located will probably not have the subscriber data base locally available, and will have to place a verifying inquiry to the roamer's home system, to access his local subscriber data base to determine his legitimacy.
The communication of this information over long distances is usually accomplished by two methods. One method is signaling system seven, while the other is known as in-channel ANI spill. Both of these mechanisms use a modem type method of transferring information.
Signaling system seven is a standard for general purpose common channel signaling, and is defined by an American National Standard for telecommunications promulgated by the American National Standards Institute, Inc. It is optimized for operation in digital telecommunications networks, and for operation over 56 or 64 kbit/s digital channels. This system is similar to packet operation, and has layers including physical, data link, network, transport, session, presentation, and application. The signaling is assumed to be below the network layer.
The signal messages have defined parts which include the routing label, circuit identification code, message type code, mandatory fixed part, mandatory available part and the optional part which may contain fixed length and variable length parameter fields.
For Example, the call reference and called party reference fields are given in Figure X. With regard to the call reference identification format, a series of octets labeled 1, 2, 3, . . . n are vertically given along side the reference field box. Horizontally, the numerals given are the eight bits which define the bit position for each octet. The first octet identifies the type of address indicator, the second the numbering plan, and the third through the nth octets identify the numerals which further identify either the called or calling party.
Signaling system seven can perform the functions of supervising the status of a line or circuit, alerting the arrival of an incoming call, addressing and routing the signals over a network.
In-channel ANI spill is a method which stands for automatic number identification. This method may include a series of digits at the front of the phone call which inform you of the identification of the phone number calling. They may arrive as digital or analog, and may be touchtone dual tone multiple frequency (DTMF) digits generated by the phone call process or in a digital form on the same circuit or on a different circuit. Thus, in-channel ANI spill is truly an amorphus designation covering a wide range of multiple methods of routing automatic number identification. ANI is associated with caller ID, and is not made available by all cellular service providers, or maybe provided with some restrictions. These restrictions can similarly limit its usefulness with respect to the more preferred signaling system seven.
Both of these methods are used to transmit information across the telephone system, including caller ID, the system which makes the caller's identification known at the called party's telephone. In the standards, there are about 100 different types of commands which can be acted upon by these systems, including inquiries and system modifications.
Further, the use of the mobile or portable telephone's specific identification number which includes both an electronic serial number (ESN) as well as the mobile identification number (MIN), will coincide with its accessibility when being called. Since a land-based or other user of the telephone system will access the mobile or portable user based upon a conventional telephone number, according to the Bellcore promulgated North American Dailing Plan, the use of a standard format telephone number as the mobile or portable telephone's identity number is efficient.
However, with the proliferation of other types of equipment and the need for multiple lines and their associated telephone numbers, today's NPA/NXX numbers are becoming an exhausted resource at a higher than ever rate. By sheer force of numbers, the numbers within each area code, and therefore the number of three digit area codes are a finite resource. The extremely infrequent use of a mobile phone still requires the assignment, and therefore the loss of, a standard NPA/NXX telephone number. Infrequent users may be persons who would only use the phone once or so per month, and individuals who keep a mobile phone for emergency use.
Unfortunately, and according to the system described above, the verification of the caller's legitimacy occurs only at one point, the home cellular system subscriber data base. The system of data-base verification operates using standard telephone numbers within its area code. Once the subscriber data base has been successfully encountered, the user has access to the system. Consequently, under current operations, a user must have an identification which is configured as a standard telephone number conforming to the North American Dialing Plan, and is not required to further identify or legitimize his identity with respect to the system.
Further, the use of the subscriber data base is subject to the procedures and requirements of the cellular telephone company. The cellular telephone company's system of allowing access, denying access, listing lost or stolen phones, improper fraud-type users, etc will always be a restrictive element. In most cases, information cannot be reported or entered at night, after most customer service centers are closed, and significant delays can occur between time of reporting and changes to the system. Further, because the cellular telephone system is monolithic with respect to its relationship with the public, the subscriber data base is configured to either allow or deny access rather than to selectively deliver differing services. In short, more specialized and selective services cannot be offered at the present time, so long as dependency is had upon conventional cellular and land line telephone system access methods.
Current access methods therefore do not allow differential access to the system, much less a higher degree of security. When a customer accesses the system to make a call, there is no guarantee that the customer, or his equipment is truly identified. Since the mobile identification number has a format matching regular North American Dialing Plan telephone numbers, it is relatively easy for persons with fraudulent intent to obtain the mobile telephone number and match the electronic serial number of another user, program this number into another type of cellular telephone equipment, access the cellular telephone system, have that equipment identified as legitimate and begin to accrue charges to the appropriated mobile telephone number account.
What is therefore needed is a non-standard, publicly non-available, non-conforming (with respect to the North American Dialing Plan) number for mobile and portable equipment, and perhaps coupled with an interactive modem-type transmission of information which positively identifies the equipment and user as legitimate.
Another disadvantage of keeping a conventional mobile phone for infrequent use is the power drain. For mobile phones, the electronics are typically powered during the times that the ignition switch is on. There is normally sufficient power to keep the associated electronics powered, although an infrequent user will expend an amount of power far more often than the telephone is used and much more often than is necessary for expected calls.
With regard to portable units, there is a current drain of the battery resource based upon being in the receive mode. In some phones, the batteries have to be recharged daily, weekly or changed monthly. Although such a frequency of recharging or replacement does not seem burdensome, it must be compared with respect to the frequency of use. For uses which are limited to emergency uses, the user will very likely forget about charging the batteries completely. If a low battery state occurs before and during an emergency, or before and during an important need, the benefits of having a portable cellular telephone will be eliminated. Further, to have relied upon the cellular telephone service may actually place the user in a worse position than would otherwise be the case if the portable telephone were not present.
Further, since conventional cellular useage is a mixture of monitoring for a call and transmitting and receiving a signal, the battery useage is difficult to predict. Even were it easy to predict, no provision has been made for insuring that the batteries are always fully charged.
Another problem with conventional cellular telephones is the accessibility of the controls, and especially on an expedited basis, such as during an emergency. In some cases the controls are lighted, but usually the controls will still require high attention and concentration in order to complete the dialing process. This is true also for 911 service and operator service. A separate button is usually activated for the send function, in addition to the keys required for entering the destination call numeric address, or telephone number.
Conventional cellular phones can pose a particular problem for sight impaired people. The sheer volume of the control buttons makes it easy for dialers to make mistakes. Further, in the event of an emergency, an excited person could have problems quickly dialing out, much less a sight impaired person. Even where the sight impaired may dial the operator to ask for dialing assistance, the operator will typically initially instruct the caller to dial the number causing the dialer to have to continually verbalize his or her handicap. This can be quite frustrating.
Further complicating the procedure is the necessity to remember and dial the telephone numbers to obtain the required help in relation to the emergency situation. Further, there is no ability for a user to tailor the usage of his phone to the types of emergency or types of uses he or she might or will usually encounter.
For example, if an infrequent user wanted to limit the use of his portable phone to 911 and calls to his home, he could not do so with a conventional mobile phone. An unauthorized user, and especially where the unauthorized use were to occur for a short time, could run up a large bill. For example, where a worker leaves his portable phone at work, or in his car, an unauthorized user could simply pick up and use the portable phone and return it to its place. Where no actual material theft of the cellular telephone hardware occurs, there is no immediate motivation to report the loss to cause de-activation of the cellular account. Indeed the unauthorized use may never be discovered, especially where the phone is active on an institutional or business account. For an individual account, the unauthorized usage will probably not be discovered until the next bill arrives, which could be up to a month or more.
Conventional landline telephone equipment has been implemented to block certain numerically defined numbers, such as numbers with the 900 area code, but equipment has not yet been formulated which would tailor a user's service to his particular needs, nor which would make system access decisions based upon his expected modes of use.
Conventional cellular telephones are also limited in their ability to perform a return call-back to the land line originating callers who unsuccessfully made calls to those mobile or portable cellular phones. Absent the caller identification system, there is no current method which will enable a called party to determine the caller identity and on telephone numbers which originated the call, to perform a manually selectable call-back of certain numbers. Even where caller identification is available, any call back will be accompanied by manual dialing activity. What is therefore needed is a system which will enable numbers to be manually selected for automatic entry into a telephone for calling back the parties which wish to call the mobile or portable telephone user.
Another system which is not currently available with conventional cellular telephones is the ability to have the cellular telephone initiate a call remotely. This feature is desired for several reasons. First, a call placed to a mobile or portable station would give an audible ring, which would have to be followed by some physical manipulation of the equipment, such as picking the receiver up, to complete the audible connection. There may be a myriad of reasons why both the calling and the called party might desire there to be no audible ringing upon the initiation of a call. There may be circumstances where a telephone is to be used for surveillance, such as listening in on a child or baby sitter, and it must be turned on and off without noise or delay.
One of the best ways to accomplish this is to alert the mobile phone to dial the call initiator. This is impossible with conventional cellular, because the conventional system can only accommodate a connection between a call initiator and completed by a call receiver's answering the call. The conventional cellular telephone system will not permit a call initiator to initiate a call to himself, from remotely located equipment. Such a feature is also useful where a sub-system owner wishes to monitor equipment.
For example, a caller may leave an emergency telephone next to a radio which is tuned to a sporting event. The user may cause his emergency telephone to initiate a call to listen in on the game. Conventional cellular is limited in that, even with automatic answer, any and all callers would be able to access the line and begin to accrue charges to the cellular telephone.
This feature, which is not available with conventional cellular technology, would be of great use and service in surveillance and remote monitoring. All of the features set forth above are not available in current cellular telephone technology. Further, the infrequent user segment of the market is not being served. With the disadvantages referred to above, there is a further need for an emergency wireless telephone which enables the very disadvantages of the current cellular system.
The needed emergency wireless telephone should be made in sufficient quantity and made sufficiently available that it can be stored for long periods of time with minimal battery dissipation, the ability to more readily predict current battery state and no need for battery replacement outside the batteries' shelf life. The needed phone would be configured and operated according to a system which supports virtually no battery dissipation, or at least a very low usage until needed. Ideally, the emergency wireless phone will be able to monitor the battery useage based upon time and call time, and provide the user with a continuing, and automatic source of replacement batteries. When needed, the emergency wireless phone should immediately switch on and automatically place the user in contact with help or assistance. The needed emergency wireless telephone should not facilitate to usage which is radically different than the usage to which the legitimate user of the telephone normally subjects to the instrument, but will always facilitate an emergency usage. The configuration of the needed emergency wireless telephone should be such that large numbers of infrequent users will enable a new class of service fitted to the needs and demands of the class.